School me on how an ammeter works

[WranglerX]

I'm wondering what would happen if his ammeter was accidentally wired like a voltmeter.

Bruce

If it's a internal shunted ammeter it going to be almost a short circuit because the shunt is a extremely low resistance... It going to either smoke the meter or blow fuses or smoke wiring because electron flow will see it as almost a direct short...

 

[number two]

Been a long time since I've had an ampmeter in a vehicle. As I recall, their indication jumps around a lot. Probably why they cut them out because they cause more alarm than help in many cases. Doesn't sound as though your alternator is charging as it should.

I remember the ammeters in '60's and '70's Dodges would wiggle around a lot!
Good Luck!

 

[Grumpycat]

I'm wondering what would happen if his ammeter was accidentally wired like a voltmeter.

Bruce

Fire.

 

[Grumpycat]

I remember the ammeters in '60's and '70's Dodges would wiggle around a lot!
Good Luck!

The Chrysler ammeters were only crude indicators. Were not driven by current through a shunt as a true ammeter but were driven by the voltage regulator in the alternator. If the alternator was producing then it moved the needle to the right, if discharging then moved the needle to the left.

I am guessing the tractor in question is wired similarly. Ammeter is connected to the regulator inside the alternator.

 

[Richard]

I seem to recall having some confusion on how mine should be wired. (memory says) I hooked the line from the alternator to the meter when I think it should have instead been the wire going to/from the starter/battery.

Whichever is correct, I initially had it wrong and had to change it.

Again, to reiterate, I'd been having some over-heating issues and it turned out my belt was VERY loose. Single belt going to fan and alternator.

I tightened it the other day and now the meter is showing slightly positive to the "C" side.

So if I have all my gremlins dealt with, does this infer that the system is charging and might be correct?

Is it also fair that as the batteries go back to a full charge during running the machine, the degree of deflection from "zero" should lesson and the meter should tend back towards zero? Or should it always show a positive charge while engine is running?

 

[Richard]

Oh, and when I cut a small section of the field afterwards, the engine temp barely went over the 1/4 hash mark when previously, I would watch it and when it go to the 3/4 hash, I'd literally shut the mower down and let the engine idle for a few minutes. I'd then resume cutting but at a lower rpm. Yesterday, the engine was screaming and the temp was about 1/4 so this is good.

 

[CausticUrbanCoast]

If your battery is good and your CCA is at or more than you need, an ammeter will stay at zero after the tractor is started. (The current going to/from the battery is too small to measure.)

 

[Fuddy1952]

I'm wondering what would happen if his ammeter was accidentally wired like a voltmeter.

Bruce

Smoke

 

[Fuddy1952]

If you have time you can test your ammeter.
You said motor not running, lights on, meter goes to first mark D (discharge) side.
1) disconnect battery (just ground neg lead)
2) reverse ammeter connections
3) connect battery back
4) lights on, meter should now go to first C (charge) side.
If it doesn't move equal ways, ammeter is bad so replace it. If it does...reconnect it the way it was (properly).

 

[lpakiz]

Ypu could view the ammeter as a 2-way water meter.
When you start your tractor and use up some watts from the battery, the charging system should replace them back into the battery. The ammeter will show how many amps are flowing back to replenish what you used.
After the battery is full, the needle should be at “0” or maybe just slightly higher.
If you turn on lights, the ammeter may twitch a little, but if the charging system can keep up or surpass what you are using, the needle should still stay at “0”
If your belt is loose, and you are using a small amount of power to run the distributor only, the needle will show a small discharge. If you turn on some lights and the charging system can’t keep up, the lights will withdraw some reserve power from the battery and the ammmeter will indicate discharge, and how much. This situation cannot continue indefinitely, because the battery will be drawn down so low that it can’t keep the ignition system going, and the engine will start to miss and stall, especially at full throttle.
Again, like a 2-way water meter, the ammeter shows you how much current is flowing, and which way it’s going.